Procarbazine H Cl will be used to test its immunosuppressive effects in the mouse - T. spiralis model, and the results compared directly to those obtained in our published work on ATS. Worm counts, and serologic and histopathologic responses will be the main parameters. The blastogenic response of splenic T-cells after interaction with various different antigens, including Melcher's acid- soluble protein fraction, will be studied. If this in vitro model of D H is perfected, various larvae fractions will be tested in attempts to isolate one(s) with strong D H - producing qualities. Studies will be made with the PCA test in attempts to demonstrate hemocytotropic antibodies in the sera of our donor mice before collecting spleen cells, and in the recipients after the transfer of cells.